1. Technical Field
This invention relates to a power source apparatus containing rechargeable batteries and in particular to a power source apparatus suitable as backup power supply.
2. Description of Related Art
A power source apparatus that houses rechargeable batteries can supply power to a load from the rechargeable batteries. Therefore, it can supply power to the load even during a power outage. The power source apparatus is maintained in a state in which rechargeable batteries are charged when there is no power outage, and power can be supplied to a load during a power outage. If the rechargeable batteries of this power source apparatus are charged at the voltage of an (external) power source, power that can be supplied during a power outage will be at a lower voltage. This is because the voltage of rechargeable batteries charged by a power source will be lower than that charging voltage, and rechargeable battery voltage will further decrease as the batteries discharge. To eliminate this drawback, a power source apparatus has been developed that boosts the power source voltage to charge the rechargeable batteries (refer to Japanese Laid-Open Patent Publication No. 2005-304142).